1. Field of the Invention
This invention relates to a paper feeder apparatus for use with an image forming apparatus such as copier, facsimile machine, and printer to feed recording paper sheets to a main body of the image forming apparatus for image formation.
2. Description of the Prior Art
There have been known a detachably attachable feeder apparatus (generally, in the form of paper feeder deck) which is disposed on a side of a main body of an image forming apparatus such as copier, facsimile machine, and printer, and accommodates as large as several thousands of sheets therein. Such a feeder apparatus comprises a sheet stacker on which several thousands of sheets are stacked, a sheet stacker elevating mechanism for drivingly moving the sheet stacker up and down, and a feeding mechanism disposed above the sheet stacker to dispense the sheets one by one toward the apparatus main body. The sheet stacker elevating mechanism is actuated to move the sheet stacker upward stepwise as the sheets are dispensed one by one so that the sheets stacked on the sheet stacker are fed to the feeding mechanism one by one.
The feeder apparatus is equipped with a door so that an operator accesses inside the feeder apparatus to replenish sheets therein. The door is formed on either a side portion or an upper portion of the feeder apparatus.
In the case of a feeder apparatus provided with a side door, the sheet stacker is lowered prior to opening of the side door. Upon lowering of the sheet stacker, the side door is allowed to open so that the operator can replenish sheets into the feeder apparatus. In this type of feeder apparatus, up and down movement of the sheet stacker is prohibited during opening of the side door because the upper and lower spaces above and below the sheet stacker are exposed outside during the opening of the side door which resultantly may cause intrusion of foreign matters in an element inside the feeder apparatus. The above type of feeder apparatus makes it easier to replenish sheets because the operator is enabled to stack sheets on the sheet stacker through a side opening defined by opening of the side door. This type of feeder apparatus, however, has a limitation for installation because the feeder apparatus requires an additional space which allows the operator to open the side door.
In the case of a feeder apparatus provided with a top door, the operator opens the top door first. Upon confirming that the top door has been opened, the sheet stacker is lowered stepwise. When the sheet stacker is lowered to a certain position, sheet replenishing operation is allowed. In this type of feeder apparatus, upward movement of the sheet stacker during opening of the top door is prohibited because the upper space above the sheet stacker is exposed outside during the opening of the top door and foreign matters may likely to intrude in an element inside the feeder apparatus during the opening.
In the latter type of feeder apparatus, sheet replenishing can be performed by opening the top door which is easily accessible for an operator standing generally in front of the image forming apparatus main body. This type of feeder apparatus has less limitation for installation because the feeder apparatus does not require an additional space which is required for the former type of feeder apparatus. The latter type of feeder apparatus, however, has a difficulty in securing a large opening at an upper part of the feeder apparatus because the feeding mechanism is provided at the upper part of the feeder apparatus. In addition to this disadvantage, replenishing of sheets through the upper opening involves vertical movement for the operator to stack the sheets onto the sheet stacker. This stacking operation by the operator may likely to cause damage of corner end(s) of the sheet(s) or displaced stacking onto the sheet stacker.
An object of this invention is to provide a paper feeder apparatus for use with an image forming apparatus which has solved the aforementioned problems residing in the prior art.
Another object of the invention is to provide a paper feeder apparatus which has less limitation for installation and enables an operator to adequately replenish sheets depending on the installed place for the image forming apparatus.
According to an aspect of the invention, a feeder apparatus is arranged on a side of a main boy of an image forming apparatus. The feeder apparatus comprises a housing having a top opening and a vertical opening, a sheet stacker provided in the housing for holding a stack of sheets thereon, an elevating drive mechanism for moving the sheet stacker up and down, a feeding mechanism provided above the sheet stacker to feed the sheets one by one in a sheet transport direction to the image forming apparatus main body, a top door for closing and opening the top opening and allowing an operator to replenish sheets onto the sheet stacker from the top opening in an opened state, and a vertical door for closing and opening the vertical opening and allowing an operator to replenish sheets onto the sheet stacker from the vertical opening in an opened state.
With this arrangement, the operator is enabled to replenish sheets onto the sheet stacker by opening the top door. This arrangement enables to install the image forming apparatus in a relatively small space. In the case where there is provided a space sufficient for allowing the operator to open the vertical door, the operator can select a sheet replenishing manner depending on a situation such that the top door is opened to replenish a small number of sheets and the vertical door is opened to replenish a large number of sheets.
These and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description and accompanying drawings.